What does the writer mean by ‘the fiery misery’ of those subjected to make-up?

The make-up room of Gemini Studios looked like a haircutting salon. It had around half a dozen mirrors with incandescent lights at all angles around them. The artists would feel the heat coming from these lights. Thus, the writer uses the term ‘fiery misery’ to denote the uncomfortable situation of those subjected to make-up.